ege27.kt

fun main(args: Array<String>) {
    val pairs = (1..readLine()!!.toInt()).map {
        val (a, b) = readLine()!!.split(' ').map(String::toInt)
        Pair<Int, Int>(Math.min(a, b), Math.max(b, a))
    }
    print(when {
        pairs.all { it.first % 3 == 0 && it.second % 3 == 0 } -> 0  // Has no answers
        else -> {
            val sum = pairs.sumBy { it.first }
            when {
                sum % 3 != 0 -> sum           // Sum not divisible by 3
                else -> sum + pairs.map { it.second - it.first }.filter { it % 3 != 0 }.min()!!.toInt()     // Minimal answer
            }
        }
    })
}